Research papers, peer-reviewed

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Helama S. (2012): A Review of Citation Patterns in Doctoral Dissertations at the Department of Geology, University of Helsinki, Finland, since 1896. Science & Technology Libraries 31, 180-189.

Tian Q. H., Zhou X. J., Gou X. H., Zhao P., Fan Z. X. & Helama S. (2012): Analysis of reconstructed annual precipitation from tree-rings for the past 500 years in the middle Qilian Mountain. Science China Earth Sciences 55, 770-778.

Helama S., Bégin Y., Vartiainen, M., Peltola, H., Kolström, T. & Meriläinen, J. (2012): Quantifications of dendrochronological information from contrasting microdensitometric measuring circumstances of experimental wood samples. Applied Radiation and Isotopes 70, 1014-1023.

Helama S.
, Seppä, H., Bjune, A. E. & Birks, H. J. B. (2012): Fusing pollen-stratigraphic and dendroclimatic proxy data to reconstruct summer temperature variability during the past 7.5 ka in subarctic Fennoscandia. Journal of Paleolimnology 48, 272-286. DATA

Holopainen J.
, Rickard I. J. & Helama S. (2012): Climatic signatures in crops and grain prices in 19th-century Sweden. The Holocene 22, 939-945.

Helama S. & Holopainen J. (2012): Spring temperature variability relative to the North Atlantic Oscillation and sunspots - A correlation analysis with a Monte Carlo implementation. Palaeogeography, Palaeoclimatology, Palaeoecology 326-328, 128-134.

Helama S.
, Hyttinen O. & Salonen V.-P. (2012): Late Weichselian varve archives re-explored to assess proglacial sedimentary chronologies using the principles of tree-ring analysis. Progress in Physical Geography 36, 188-209.

Helama S., Läänelaid A., Raisio J. & Tuomenvirta H. (2012): Mortality of urban pines in Helsinki explored using tree rings and climate records. Trees 26, 353-362

Läänelaid A.
, Helama S., Kull A., Timonen M. & Jaagus, J. (2012): Common growth signal and spatial synchrony of the chronologies of tree-rings from pines in the Baltic Sea region over the last nine centuries. Dendrochronologia 30, 147-155.

Macias-Fauria M., Grinsted A., Helama S. & Holopainen J. (2012): Persistence matters: Estimation of the statistical significance of paleoclimatic reconstruction statistics from autocorrelated time series. Dendrochronologia 30, 179-187. CODE

Tian Q., Helama S. & Zhao P. (2011): Temperature variability inferred from tree rings of Qinling region in north-central China. In: Wang W., Yang S., Guan W., Yang H. & Li Y. (eds.): 2011 International Symposium on Water Resource and Environmental Protection (ISWREP). May 20-22, 2011, Xi’an, Shaanxi Province, China. ISBN: 978-1-61284-339-1, DOI: 10.1109/ISWREP.2011.5893669, pp. 2072-2075.

Büntgen U., Raible C.C., Frank D., Helama S., Cunningham L., Hofer D., Nievergelt D., Verstege A., Timonen M., Stenseth N.C. & Esper J. (2011): Causes and Consequences of Past and Projected Scandinavian Summer Temperatures, 500-2100 AD. PLoS ONE 6 (9): e25133. DOI: 10.1371/journal.pone.0025133.

Helama S., Tuomenvirta H. & Venäläinen A. 2011: Boreal and subarctic soils under climatic change. Global and Planetary Change 79, 37-47.

Hordo M., Henttonen H. M., Mäkinen H., Helama S. & Kiviste A. (2011): Annual growth variation of Scots pine in Estonia and Finland. Baltic Forestry 17, 35-49.

Helama S. (
2011): Sclerochronology – Mussels as Bookkeepers of Aquatic Environment. In: McGevin L. E. (ed.): Mussels: Anatomy, Habitat and Environmental Impact. Hauppauge, Nova Science Publishers. ISBN: 978-1-61761-763-8, pp. 395-412.

Helama S.
& Hood B.C. (2011): Stone Age midden deposition assessed by bivalve sclerochronology and radiocarbon wiggle-matching of Arctica islandica shell increments. Journal of Archaeological Science 38, 452-460.

Moir A.K., Leroy, S.A.G. & Helama S. (2011): Role of substrate on the dendroclimatic response of Scots pine from varying elevations in northern Scotland. Canadian Journal of Forest Research 41, 822-838.

Ogurtsov M.G., Jungner H., Helama S., Lindholm M. & Oinonen M. (2011): Paleoclimatological evidence for unprecedented recent temperature rise at the extratropical part of the Northern Hemisphere.
Geografiska Annaler: Series A, Physical Geography 93, 17-26.

Hood B.C. & Helama S. (2010): Karlebotnbakken Reloaded: Shifting the Chronological Significance of an Iconic Late Stone Age Site in Varangerfjord, North Norway. Fennoscandia Archaeologica 27, 35-43.

Rickard I.J., Holopainen J., Helama S., Helle S., Russell A.F. & Lummaa V. (2010): Food availability at birth limited reproductive success in historical humans. Ecology 91, 3515-3525.
Research highlights: The New York Times January 3, 2011. LINK

Helama S.
, Eronen M. & Timonen M. (2010): Dendroécologie des bois fossiles dans le nord de la Laponie. In: Payette S. & Filion L. (eds.): La Dendroécologie: Principes, méthodes et applications. Presses de l’Université Laval, Québec. Québec. ISBN: 978-2-7637-9086-2, pp. 709-730.

Helama S.
, Seppä, H., Birks, H.J.B. & Bjune, A.E. (2010): Reconciling pollen-stratigraphical and tree-ring evidence for high- and low-frequency temperature variability in the past millennium. Quaternary Science Reviews 29, 3905-3918.

Helama S.
, Macias Fauria M., Mielikäinen K., Timonen M. & Eronen M. (2010): Sub-Milankovitch solar forcing of past climates: mid and late Holocene perspectives. Geological Society of America Bulletin 122, 1981-1988

Holopainen J.
, Helama S. & Partonen T. (2010): Memes and Finnish suicide. Journal of Social Medicine 47, 174-186.

Helama S.
, Läänelaid A., Tietäväinen H., Macias Fauria M., Kukkonen I.T., Holopainen J., Nielsen J.K. & Valovirta I. (2010): Late Holocene climatic variability reconstructed from incremental data from pines and pearl mussels – a multi-proxy comparison of air and subsurface temperatures. Boreas 39, 734-748.

Luoto T.P. & Helama S. (2010): Palaeoclimatological and palaeolimnological records from fossil midges and tree-rings: the role of the North Atlantic Oscillation in eastern Finland through the Medieval Climate Anomaly and Little Ice Age. Quaternary Science Reviews 29, 2411-2423.

Helama S.
& Holopainen J. (2010): Climate change and pure geography: proximity, landscape and cartography in the context of J.G. Granö’s theory. Alue ja Ympäristö 39, 3-14.

Macias Fauria M.
, Grinsted A., Helama S., Moore J., Timonen M., Martma T., Isaksson E. & Eronen M. (2010): Unprecedented low twentieth century winter sea ice extent in the Western Nordic Seas since A.D. 1200. Climate Dynamics 34, 781-795.

Helama S., Vartiainen M., Kolström T. & Meriläinen J. (2010): Dendrochronological investigation of wood extractives. Wood Science and Technology 44, 335-351.

Helle S., Helama S. & Lertola K. (2009): Evolutionary ecology of human birth sex ratio under the compound influence of climate change, famine, economic crises and wars. Journal of Animal Ecology 78, 1226-1233.

Ogurtsov M.G., Jungner H.., Lindholm M., Helama S. & Dergachev V.A. (2009): Quasisecular Cyclicity in the Climate of the Earth’s Northern Hemisphere and Its Possible Relation to Solar Activity Variations. Geomagnetism and Aeronomy 49, 1056-1062.

Helama S., Nielsen J.K., Macias Fauria M. & Valovirta I. (2009): A fistful of shells: amplifying sclerochronological and palaeoclimate signals from molluscan death assemblages. Geological Magazine 146, 917-930.

Helama S., Timonen M., Holopainen J., Ogurtsov M.G., Mielikäinen K., Eronen M., Lindholm M. & Meriläinen J. (2009): Summer temperature variations in Lapland during the Medieval Warm Period and the Little Ice Age relative to natural instability of thermohaline circulation on multi-decadal and multi-centennial scales. Journal of Quaternary Science 24, 450-456.

Helama S., Läänelaid A., Raisio J. & Tuomenvirta H. (2009): Oak decline in Helsinki portrayed by tree-rings, climate and soil data. Plant and Soil 319, 163-174.

Helama S., Nielsen J.K. & Valovirta I. (2009): Evaluating contemporaneity and post-mortem age of malacological remains using sclerochronology and dendrochronology. Archaeometry 51, 861-877.

Holopainen J. & Helama S. (2009): Little Ice Age Farming in Finland: Preindustrial Agriculture on the Edge of the Grim Reaper’s Scythe. Human Ecology 37, 213-225.

Helama S., Makarenko N.G., Karimova L.M., Kruglun O.A., Timonen M., Holopainen, J., Meriläinen J. & Eronen M. (2009): Dendroclimatic transfer functions revisited: Little Ice Age and Medieval Warm Period summer temperatures reconstructed using artificial neural networks and linear algorithms. Annales Geophysicae 27, 1097-1111.

Macias Fauria M. & Johnson E.A. (2009): Large-scale climatic patterns control area affected by mountain pine beetle in British Columbia, Canada. Journal of Geophysical Research 114, DOI: 10.1029/2008JG000760.

Helama S.
, Meriläinen J. & Tuomenvirta H. (2009)
: Multicentennial megadrought in northern Europe coincided with a global El Niño–Southern Oscillation drought pattern during the Medieval Climate Anomaly. Geology 37, 175-178.

Holopainen J.
, Helama S., Kajander J. M., Korhonen J., Launiainen J., Nevanlinna H., Reissell A. & Salonen V.-P. (2009): A multiproxy reconstruction of spring temperature in south-west Finland since AD 1750.
Climatic Change 92, 213-233.

Macias Fauria M., Helle, T., Niva, A., Posio, H. & Timonen, M. (2008): Removal of lichen mat by reindeer enhances tree-growth in a northern Scots pine forest. Canadian Journal of Forest Research 38, 2981-2993.

Helama S., Vartiainen M., Kolström T., Peltola H. & Meriläinen J. (2008): X-ray microdensitometry applied to subfossil tree-rings - growth characteristics of ancient pines from the southern boreal forest zone in Finland, at intra-annual to centennial time-scales. Vegetation History and Archaeobotany 17, 675-686.

Helle S., Käär P., Helama S. & Jokela J. (2008): Do humans adjust offspring sex according to local operational sex ratio? Evolutionary Ecology Research 10, 775-785.

Helama S., Mielikäinen K., Timonen M. & Eronen M. (2008): Finnish supra-long tree-ring chronology extended to 5634 BC. Norsk Geografisk Tidsskrift-Norwegian Journal of Geography 62, 271-277.

Helama S. & Nielsen, J. K. (2008): Construction of statistically reliable sclerochronology using subfossil shells of river pearl mussel. Journal of Paleolimnology 40, 247-261.

Macias Fauria M. & Johnson E.A. (2008): Climate and wildfires in the North American boreal forest. Philosophical transactions of the Royal Society of London. Series B, Biological sciences 363, 2317-2329.

Macias Fauria M. (2008): Ecological processes and large-scale climate relationships in northern coniferous forests. Doctoral dissertation. Department of Geology, University of Helsinki.

Briffa, K.R., Shishov, V.V., Melvin, T.M., Vaganov, E.A., Grudd, H., Hantemirov, R.M. Eronen, M. & Naurzbaev, M.M. (2008): Trends in recent temperature and radial tree growth spanning 2000 years across northwest Eurasia. Philosophical transactions of the Royal Society of London. Series B, Biological sciences 363, 2271-2284.

Larsen L.B., Vinther, B.M., Briffa, K.R., Melvin, T.M., Clausen, H.B., Jones, P.D., Siggaard-Andersen, M.-L., Hammer, C.U., Eronen, M., Grudd, H., Gunnarson, B.E., Hantemirov, R.M., Naurzbaev, M.M. & Nicolussi, K. (2008): New ice core evidence for a volcanic cause of the A.D. 536 dust veil. Geophysical Research Letters 35, DOI: 10.1029/2007GL032450.

Ogurtsov M.G., Raspopov O.M., Helama S., Oinonen M., Lindholm M., Jungner H. & Meriläinen J. (2008): Climatic variability along a north-south transect of Finland over the last 500 years: Signature of solar influence or internal climate oscillations? Geografiska Annaler: Series A, Physical Geography 90, 141-150.

Helama S., Salminen H., Timonen M. & Varmola M. (2008): Dendroclimatological analysis of seeded and thinned Scots pine (Pinus sylvestris L.) stands at the coniferous timberline. New Forests 35, 267-284.

Helama S. & Valovirta I. (2008): The oldest recorded animal in Finland: ontogenetic age and growth in Margaritifera margaritifera (L. 1758) based on internal shell increments. Memoranda Societatis pro Fauna et Flora Fennica 84, 20-30.

Helle S., Helama S. & Jokela J. (2008): Temperature-related birth sex ratio bias in historical Sami: warm years bring more sons. Biology Letters 4, 60-62. Research highlights: Nature 450: 765.

Helle S. & Helama S. (2007): Climatic Variability and the Population Dynamics of Historical Hunter-Gatherers: The Case of Sami of Northern Finland. American Journal of Human Biology 19, 844-853.

Andreu L., Gutiérrez E., Macias M., Ribas M., Bosch O. & Camarero J. J. (2007): Climate increases regional tree growth variability in Iberian pine forests. Global Change Biology 13, 804-815.

Helama S.
, Schöne B. R., Kirchhefer A. J., Nielsen J. K., Rodland D. L. & Janssen R. (2007): Compound response of marine and terrestrial ecosystems to varying climate: pre-anthropogenic perspective from bivalve shell growth increments and tree-rings. Marine Environmental Research 63, 185-199.

Karimova L., Kuandykov Y., Makarenko N., Novak M. M. & Helama S. (2007): Fractal and topological dynamics for the analysis of paleoclimatic records. Physica A 373, 737-746.

Macias M., Andreu L., Bosch O., Camarero J. J. & Gutiérrez E. (2006): Increasing aridity is enhancing Silver fir (Abies alba Mill.) water stress in its south-western distribution limit. Climatic Change 79, 289-313.

Macias Fauria M.
& Johnson. E.A. (2006): Large-scale climatic patterns control large lightning fire occurrence in Canada and Alaska forest regions. Journal of Geophysical Research 111, G04008, DOI: 10.1029/2006JG000181.

Holopainen J. (2006): Reconstructions of past climates from documentary and natural sources in Finland since the 18th century. Doctoral dissertation. Department of Geology, University of Helsinki.

Holopainen J., Helama S. & Timonen M. (2006): Plant phenological data and tree-rings as palaeoclimate indicators since AD 1750 in SW Finland. International Journal of Biometeorology 51, 61-72.

Helama S., Schöne B. R., Black, B. A. & Dunca, E. (2006): Constructing long-term proxy series for aquatic environments with absolute dating control using a sclerochronological approach: introduction and advanced applications. Marine and Freshwater Research 57, 591-599.

Helama S., Timonen M., Lindholm M. Meriläinen, J. & Eronen M. (2005): Extracting long-period climate fluctuations from tree-ring chronologies over timescales of centuries to millennia. International Journal of Climatology 25, 1767-1779.

Helama S., Lindholm M., Timonen M. & Eronen M. (2005): Mid- and late Holocene tree population density changes in northern Fennoscandia derived by a new method using megafossil pines and their tree-ring series. Journal of Quaternary Science 20, 567-575.

Helama S.
, Lindholm M., Meriläinen J., Timonen M. & Eronen M. (2005): Multicentennial ring-width chronologies of Scots pine along north-south gradient across Finland. Tree-Ring Research 61, 21-32.

Ogurtsov M. G., Helama S., Eronen M. & Lindholm M. (2005): Centennial-to-millennial fluctuations in July temperatures in North Finland as recorded by timberline tree rings of Scots pine. Quaternary Research 63, 182-188.

Macias M., Timonen M., Kirchhefer A., Lindholm M., Eronen M. & Gutiérrez E. (2004): Growth variability of Scots pine (Pinus sylvestris) along a west-east gradient across northern Fennoscandia: A dendroclimatic approach. Arctic, Antarctic and Alpine Research 36, 565-574.

Helama S.
, Lindholm M., Timonen M. & Eronen M. (2004): Dendrochronologically dated changes in the limit of pine in northernmost Finland during the past 7.5 millennia. Boreas 33, 250-259.

Helama S., Holopainen J., Timonen M., Ogurtsov M. G., Lindholm M., Meriläinen J. & Eronen M. (2004): Comparison of living-tree and subfossil ring-widths with summer temperatures from 18th, 19th and 20th centuries in northern Finland. Dendrochronologia 21, 147-154.

Makarenko N., Danilkina Y., Karimova L., Kuandykov Y., Eronen M. & Helama S. (2004): The estimation of the interrelation between paleoclimatic time series. In: Proceedings of the International Astronomical Union. Volume 2004. Issue IAUS223. Multi-Wavelength Investigations of Solar Activity. Cambridge University Press. pp 123-124.

Helama S. (2004): Forest fragmentation due to long-term forest-limit retreat in northern Finland. In: Sano, M., Miyamoto, A. & Sugimura K. (eds.): Proceedings of IUFRO International Workshop on Landscape Ecology 2004. Conservation and Management of Fragmented Forest Landscapes. October 25-28, 2004, Tsukuba, Ibaraki, Japan. ISBN 4-902606-01-1, pp. 96-99.

Ogurtsov M.G., Jungner H., Kocharov G.E., Lindholm M. & Eronen M. (2004): Nitrate Concentration in Greenland Ice: an Indicator of Changes in Fluxes of Solar and Galactic High-Energy Particles. Solar Physics 222, 177-190.

Helama S., Lindholm M., Timonen M. & Eronen M. (2004): Detection of climate signal in dendrochronological data analysis: a comparison of tree-ring standardization methods. Theoretical and Applied Climatology 79, 239-254.

Helama S. (2004): Millennia-long tree-ring chronologies as records of climate variability in Finland. Doctoral dissertation. Department of Geology, University of Helsinki.

Helama S. & Lindholm M. (2003): Droughts and rainfall in south-eastern Finland since AD 874, inferred from Scots pine ring-widths. Boreal Environmental Research 8, 171-183.

Ogurtsov M.G., Jungner H., Kocharov G.E., Lindholm M., Eronen M. & Nagovitsyn Yu. A. (2003): On the link between northern Fennoscandian climate and length of the quasi-eleven-year cycle in galactic cosmic-ray flux. Solar Physics 218, 345-357.

Eronen M., Lindholm M., Helama S., Meriläinen J. & Timonen M. (2003): Low- and high frequency summer temperature changes from tree-ring archieve of Fennoscandian forest-limit Scots pine. PAGES News 11 (2-3), 14-15.

Läänelaid A. (2002): Tree-ring dating in Estonia. Doctoral dissertation. Department of Geology, University of Helsinki.

Lindholm M., Eronen M. & Helama S. (2002): Recent Fennoscandian Pine Records of Temperature, Precipitation and the North Atlantic Oscillation. PAGES News 10 (1), 20.

Ogurtsov M.G., Kocharov G. E., Lindholm M., Meriläinen J., Eronen, M. & Nagovitsyn, Yu. A. (2002): Evidence of solar variation in  tree-ring-based climate reconstructions. Solar Physics 205, 403-417.

Eronen M., Zetterberg P., Briffa K.R., Lindholm M., Meriläinen J. & Timonen M. (2002): The supra-long Scots pine tree-ring record for Finnish Lapland - 1: chronology construction and initial inferences. The Holocene 12, 673-680.

Payette S., Eronen M. & Jasinski P. (2002): Late Pleistocene and Holocene changes of the circumboreal Taiga-Tundra interface. Ambio Special Report 12, 15-22.

Helama S., Lindholm M., Timonen M., Meriläinen J. & Eronen M. (2002): The supra-long Scots pine tree-ring record for Finnish Lapland: Part 2, interannual to centennial variability in summer temperatures for 7500 years. The Holocene 12, 681-687.

Ogurtsov M.G., Kocharov G.E., Lindholm M., Eronen M., Nagovitsyn Yu.A. (2001): Solar activity and regional climate. Radiocarbon 43, 439-449.